Multipath Time Delay Estimation And Modeling Of Wireless Channel

The wireless channel is the core of the wireless communication. The wirelesschannel measurement is the most direct way to study the propagation characteristics ofthe wireless channel. The propagation delay of each path is the main parameter ofwireless channel measurement. The main measurement parameter of the wirelesschannel measurement is the propagation delay of each path.Spread spectrum sliding correlation method is most commonly used in the existingchannel measurement methods. Its main idea is to use the good autocorrelation of thespread spectrum code to distinguish multipath signals. However, the resolution of themethod is limited by the chip duration. And the chip duration determines the signalbandwidth. The improvement of time resolution can’t rely on the reduction of the chipduration when the bandwidth of the system is limited. We need to look for some ways toimprove the time resolution.This paper firstly studies the spread spectrum sliding correlation method. And thenseveral super-resolution algorithms which can improve the time resolution are studied.They are MPOC algorithm, EM algorithm and WRELAX algorithm. Their principlesare introduced in this paper. And then the three algorithms are simulated and theirperformance is analyzed. This paper has studied several improved methods of EMalgorithm and has made a comparison between EM algorithm and WRELAX algorithm.Field tests of wireless communication system often have certain requirements onthe channel environment. It is difficult to find the proper channel environmentsometimes. The channel simulator can simulate the needed wireless channelenvironment in the laboratory and achieve the same objective with a field test.Another part of this paper is to study the method of channel modeling and thedesign of wireless channel simulator. The sine wave superposition method and theshaping filter method are two main methods of wireless channel modeling. And theshaping filter method need to consume a large amount of filter resources. Because theresource of software radio platform is limited, this paper mainly studies the Jakessimulator which is based on the wave superposition method. I simulate Jakes simulator and analyze its performance in SIMULINK. I completed the hardware implementationof the flat fading channel and the frequency selective channel by SDR platform. Andthen I test the channel simulator and analyze its performance.Finally, I use the existing equipment of laboratory to build a wireless multipathtime delay measurement system. I put the super resolution time delay estimationalgorithm into the system and it improves the time delay resolution of the system. ThenI use the system to measure and analyze the delay characteristics of the channelsimulator and the actual field channel.